Florence is on track to slow down significantly after landfall. And the longer a hurricane hovers over land, the more rain it dumps on the same place.

“With this storm, what’s unique is it’s forecast to stall … dropping copious amounts of rainfall across the Carolinas and into Virginia,” Long said. “So this is not just going to be a coastal threat. It’s a statewide threat for the states involved.”

Some areas could get deluged with 20 inches of rain, Myers said.

The problem is, much of the Carolinas are already saturated from rainfall. So the land can’t absorb much more water.

“Inland flooding will be a major threat and something people far from the landfall location should be concerned about,” CNN meteorologist Brandon Miller said.

It’s barreling toward people not used to big hurricanes

If the latest forecast holds, Florence will strike farther north on the East Coast than any other Category 4 hurricane in history.

The Carolinas will likely bear the brunt of Florence’s wrath. But that part of the East Coast rarely sees any major hurricanes.

And in the 29 years since Hurricane Hugo struck, the population of the coastal Carolinas has skyrocketed.

“There’s 25 percent more people living between Charleston (South Carolina) and Morehead City (North Carolina) than there were when Hugo was making landfall,” Myers said.

“Many of the people here have never seen a storm this strong,” Myers said.

“They have no idea what ‘overwash’ of an island will do to a home, what the wind could do to your home and what to do to your home to make it safer after you evacuate.”

Even Wilmington, North Carolina — a coastal city accustomed to severe weather — is bracing for an unusually brutal impact.

“We’re a resilient bunch down here. We go through a lot of these hurricane scares throughout the years,” Wilmington Mayor Bill Saffo said. “But this is pretty serious.”

He warned residents to take precautions “because once this storm is upon us, we’re not going to be able to send emergency personnel out to rescue you.”